forked from Minki/linux
197ecb3802
Scrubbing pages on initial balloon down can take some time, especially in nested virtualization case (nested EPT is slow). When HVM/PVH guest is started with memory= significantly lower than maxmem=, all the extra pages will be scrubbed before returning to Xen. But since most of them weren't used at all at that point, Xen needs to populate them first (from populate-on-demand pool). In nested virt case (Xen inside KVM) this slows down the guest boot by 15-30s with just 1.5GB needed to be returned to Xen. Add runtime parameter to enable/disable it, to allow initially disabling scrubbing, then enable it back during boot (for example in initramfs). Such usage relies on assumption that a) most pages ballooned out during initial boot weren't used at all, and b) even if they were, very few secrets are in the guest at that time (before any serious userspace kicks in). Convert CONFIG_XEN_SCRUB_PAGES to CONFIG_XEN_SCRUB_PAGES_DEFAULT (also enabled by default), controlling default value for the new runtime switch. Signed-off-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com> Reviewed-by: Juergen Gross <jgross@suse.com> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
259 lines
7.0 KiB
C
259 lines
7.0 KiB
C
/******************************************************************************
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* Xen balloon driver - enables returning/claiming memory to/from Xen.
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*
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* Copyright (c) 2003, B Dragovic
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* Copyright (c) 2003-2004, M Williamson, K Fraser
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* Copyright (c) 2005 Dan M. Smith, IBM Corporation
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License version 2
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* as published by the Free Software Foundation; or, when distributed
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* separately from the Linux kernel or incorporated into other
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* software packages, subject to the following license:
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this source file (the "Software"), to deal in the Software without
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* restriction, including without limitation the rights to use, copy, modify,
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* merge, publish, distribute, sublicense, and/or sell copies of the Software,
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* and to permit persons to whom the Software is furnished to do so, subject to
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* the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
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* IN THE SOFTWARE.
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/kernel.h>
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#include <linux/errno.h>
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#include <linux/mm_types.h>
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#include <linux/init.h>
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#include <linux/capability.h>
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#include <xen/xen.h>
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#include <xen/interface/xen.h>
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#include <xen/balloon.h>
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#include <xen/xenbus.h>
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#include <xen/features.h>
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#include <xen/page.h>
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#include <xen/mem-reservation.h>
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#define PAGES2KB(_p) ((_p)<<(PAGE_SHIFT-10))
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#define BALLOON_CLASS_NAME "xen_memory"
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static struct device balloon_dev;
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static int register_balloon(struct device *dev);
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/* React to a change in the target key */
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static void watch_target(struct xenbus_watch *watch,
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const char *path, const char *token)
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{
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unsigned long long new_target, static_max;
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int err;
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static bool watch_fired;
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static long target_diff;
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err = xenbus_scanf(XBT_NIL, "memory", "target", "%llu", &new_target);
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if (err != 1) {
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/* This is ok (for domain0 at least) - so just return */
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return;
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}
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/* The given memory/target value is in KiB, so it needs converting to
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* pages. PAGE_SHIFT converts bytes to pages, hence PAGE_SHIFT - 10.
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*/
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new_target >>= PAGE_SHIFT - 10;
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if (!watch_fired) {
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watch_fired = true;
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err = xenbus_scanf(XBT_NIL, "memory", "static-max", "%llu",
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&static_max);
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if (err != 1)
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static_max = new_target;
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else
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static_max >>= PAGE_SHIFT - 10;
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target_diff = (xen_pv_domain() || xen_initial_domain()) ? 0
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: static_max - balloon_stats.target_pages;
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}
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balloon_set_new_target(new_target - target_diff);
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}
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static struct xenbus_watch target_watch = {
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.node = "memory/target",
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.callback = watch_target,
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};
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static int balloon_init_watcher(struct notifier_block *notifier,
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unsigned long event,
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void *data)
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{
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int err;
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err = register_xenbus_watch(&target_watch);
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if (err)
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pr_err("Failed to set balloon watcher\n");
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return NOTIFY_DONE;
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}
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static struct notifier_block xenstore_notifier = {
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.notifier_call = balloon_init_watcher,
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};
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void xen_balloon_init(void)
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{
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register_balloon(&balloon_dev);
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register_xen_selfballooning(&balloon_dev);
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register_xenstore_notifier(&xenstore_notifier);
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}
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EXPORT_SYMBOL_GPL(xen_balloon_init);
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#define BALLOON_SHOW(name, format, args...) \
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static ssize_t show_##name(struct device *dev, \
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struct device_attribute *attr, \
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char *buf) \
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{ \
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return sprintf(buf, format, ##args); \
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} \
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static DEVICE_ATTR(name, S_IRUGO, show_##name, NULL)
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BALLOON_SHOW(current_kb, "%lu\n", PAGES2KB(balloon_stats.current_pages));
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BALLOON_SHOW(low_kb, "%lu\n", PAGES2KB(balloon_stats.balloon_low));
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BALLOON_SHOW(high_kb, "%lu\n", PAGES2KB(balloon_stats.balloon_high));
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static DEVICE_ULONG_ATTR(schedule_delay, 0444, balloon_stats.schedule_delay);
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static DEVICE_ULONG_ATTR(max_schedule_delay, 0644, balloon_stats.max_schedule_delay);
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static DEVICE_ULONG_ATTR(retry_count, 0444, balloon_stats.retry_count);
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static DEVICE_ULONG_ATTR(max_retry_count, 0644, balloon_stats.max_retry_count);
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static DEVICE_BOOL_ATTR(scrub_pages, 0644, xen_scrub_pages);
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static ssize_t show_target_kb(struct device *dev, struct device_attribute *attr,
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char *buf)
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{
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return sprintf(buf, "%lu\n", PAGES2KB(balloon_stats.target_pages));
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}
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static ssize_t store_target_kb(struct device *dev,
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struct device_attribute *attr,
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const char *buf,
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size_t count)
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{
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char *endchar;
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unsigned long long target_bytes;
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if (!capable(CAP_SYS_ADMIN))
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return -EPERM;
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target_bytes = simple_strtoull(buf, &endchar, 0) * 1024;
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balloon_set_new_target(target_bytes >> PAGE_SHIFT);
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return count;
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}
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static DEVICE_ATTR(target_kb, S_IRUGO | S_IWUSR,
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show_target_kb, store_target_kb);
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static ssize_t show_target(struct device *dev, struct device_attribute *attr,
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char *buf)
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{
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return sprintf(buf, "%llu\n",
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(unsigned long long)balloon_stats.target_pages
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<< PAGE_SHIFT);
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}
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static ssize_t store_target(struct device *dev,
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struct device_attribute *attr,
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const char *buf,
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size_t count)
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{
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char *endchar;
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unsigned long long target_bytes;
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if (!capable(CAP_SYS_ADMIN))
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return -EPERM;
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target_bytes = memparse(buf, &endchar);
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balloon_set_new_target(target_bytes >> PAGE_SHIFT);
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return count;
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}
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static DEVICE_ATTR(target, S_IRUGO | S_IWUSR,
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show_target, store_target);
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static struct attribute *balloon_attrs[] = {
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&dev_attr_target_kb.attr,
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&dev_attr_target.attr,
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&dev_attr_schedule_delay.attr.attr,
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&dev_attr_max_schedule_delay.attr.attr,
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&dev_attr_retry_count.attr.attr,
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&dev_attr_max_retry_count.attr.attr,
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&dev_attr_scrub_pages.attr.attr,
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NULL
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};
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static const struct attribute_group balloon_group = {
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.attrs = balloon_attrs
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};
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static struct attribute *balloon_info_attrs[] = {
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&dev_attr_current_kb.attr,
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&dev_attr_low_kb.attr,
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&dev_attr_high_kb.attr,
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NULL
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};
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static const struct attribute_group balloon_info_group = {
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.name = "info",
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.attrs = balloon_info_attrs
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};
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static const struct attribute_group *balloon_groups[] = {
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&balloon_group,
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&balloon_info_group,
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NULL
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};
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static struct bus_type balloon_subsys = {
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.name = BALLOON_CLASS_NAME,
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.dev_name = BALLOON_CLASS_NAME,
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};
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static int register_balloon(struct device *dev)
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{
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int error;
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error = subsys_system_register(&balloon_subsys, NULL);
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if (error)
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return error;
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dev->id = 0;
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dev->bus = &balloon_subsys;
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dev->groups = balloon_groups;
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error = device_register(dev);
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if (error) {
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bus_unregister(&balloon_subsys);
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return error;
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}
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return 0;
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}
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